Unfamiliar tap and die markings.
- Thread starter Hal
- Start date
RTM
Well-known member
The Wells brothers catalogs may help. Quick glance didn’t turn anything up
Guess Answer below
I remember hearing of an “over” tap, where it was for repairing a buggered hole, so it might be a 5/8-11 tap, but 1/32 larger diameter. Not sure if you bought an over bolt after using that. Part of why they made adjustable dies, to fix a shaft.
I remember hearing of an “over” tap, where it was for repairing a buggered hole, so it might be a 5/8-11 tap, but 1/32 larger diameter. Not sure if you bought an over bolt after using that. Part of why they made adjustable dies, to fix a shaft.
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Stubby1743
Well-known member
I've never seen a tap marked like that but could the 1/32 be the thread pitch?
RoninB4
Well-known member
-There are over-sized taps. They're used to compensate for coatings, hardening of material, chrome/zinc applications, etc. They're designated with GH numbers from 1-7 in specific intervals of basic size + the oversized amount. The largest I've worked with is GH-7, which is .003-.0035 above basic size. There are supposed to be specially made taps that go above GH-7 but I've never heard of one that's 1/32 larger than basic size. Is it possible? I suppose so as there's always been a market for special taps and thread forms but it's an application I've never run into and question why a coating would need to be that thick.
-Check the thread pitch (threads per inch) to see if it's even a standard for that diameter.
-Check the thread pitch (threads per inch) to see if it's even a standard for that diameter.
I suspected they were oversized they are all standard pitch for the sizes. What puzzles me is that a general repair shop would have a complete set of oversizes. They were in a wooden box, with a die stock, but no tap handle.
Also in the box, completely unrelated, were a set of Budd wheel wrenches, and a badly abused 3/4 drive slide handle.
Also in the box, completely unrelated, were a set of Budd wheel wrenches, and a badly abused 3/4 drive slide handle.
1/32 would be 32 threads per inch. Marking says 5/8, 1/32, 11. So 5/8x 11. Standard pitch, checked with a gage.
RoninB4
Well-known member
OccupantRJ
Well-known member
Hell, I machined for 30 years and thought 1/2-12, 5/16-27, and .767-27 were already odd enough.
When I posted this, it hadn’t occurred to me to check the OD. I haven’t been back to the shop since. I will check later this morning a and post back.
That’s what I thought at first, but the thread pitches don’t match any pipe thread that I know of.
rustyzman
Well-known member
The profile of that tap looks like a Nut Tap. Long tapered lead in for production tap threading of nuts. Very low torque thread cutting because of that long lead in taper.
threadingtoolsguide.com
1/32 might be the diameter change from full thread depth to the start of the thread on that tap. That looks much too coarse to be a thread pitch for that tap, assuming that it is 5/8 diameter. The pitch looks closer to .100" or 1/10.
Now for some clarity, according to a little research here, that is a Very Old tap.
Wells Brothers & Co. was incorporated in 1879.
That changed to Wells Brothers Co. in 1888.
That tap is older than 1888 and newer than 1879.
That very much pre-dates the Unified Thread system (UNC, UNF, UNS, etc.)
5/8-10 is no longer a standard thread in the Unified Standard. That size and tap was from the days of everyone making whatever they felt was correct for the application.
A quick measurement of the OD at the thickest portion and at the very end will probably say a lot.
What exactly is a nut tap? threadingtools Guide
What a nut tap? ✅ When is it used? ✅ Nut taps are used to produce nuts with ISO standard metric threads ✅ Nut taps have a very long lead-in (2/3 of the thread length) ✅ are used for thread depths up to 1.5 x nominal diameter in short through holes ✅
threadingtoolsguide.com
1/32 might be the diameter change from full thread depth to the start of the thread on that tap. That looks much too coarse to be a thread pitch for that tap, assuming that it is 5/8 diameter. The pitch looks closer to .100" or 1/10.
Now for some clarity, according to a little research here, that is a Very Old tap.
Wells Brothers & Co. was incorporated in 1879.
That changed to Wells Brothers Co. in 1888.
That tap is older than 1888 and newer than 1879.
That very much pre-dates the Unified Thread system (UNC, UNF, UNS, etc.)
5/8-10 is no longer a standard thread in the Unified Standard. That size and tap was from the days of everyone making whatever they felt was correct for the application.
A quick measurement of the OD at the thickest portion and at the very end will probably say a lot.
RTM
Well-known member
Winner winner
The 1889 Catalog shows these
I thought it said 10 at the top of your photo?
5/8 1/32 10 is what my eyes see.
rustyzman
Well-known member
Interesting with the oversize. That is Seriously over sized at 1/32". I could see that if a nut was meant to be hot dip galvanized, perhaps.